Microphonic attachment for telephone-transmitters.



w. c. BELLOWS,

MICROPHONIC ATTACHMENT FOR TELEPHONE TRANSMITTERS.

\ APPLICATION FILED JULY 12.1916.

1,248,998. I Patented Dec. 4,1917

UNITED I STATES PATENT ornion WALTER CLARKE BELLOWS, OI! CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGN- MENTS,.TO IELOUZE MANUFACTURING COMPANY, CHICAGO, ILLINOIS, A COR- ronA'rIoN or ILLINOIS.

MICBOPI-IONIC ATTACHMENT FOB TELEPHONE TRANSMITTERS.

Specification of Letters Patent. Patented Dec. 4:, 1917.

Application filed July 12, 1916. Serial No. 108,920.

To all whom it may concern:

Be it known that I, TVALTER Lows, at Chicago, in the county of Cook and State of Illinois, have inventeda new and useful Improvement in Microphonic Attachments for Telephone-Transmitters, of which the following is a specification. V My invention relates tov improvements in theclass of devices usedas attachments'for CLARKE BEL- the mouthpieces of telephone-transmitters 1 to so augment the sounds uttered into a transmitter, that they may be in a tone so subdued as to be unintelligible to others who may be in the roomwith, or near the user of the telephone, but clearly audible to a listener at the receiving end. 7

One object of my invention is to provide an improved construction of attachment in the class referred to, with the advantage, among other advantages, of greatly aug menting the microphonic efiect, so that even whispered speech will be rendered clearly audible at the receiving end of the telephone; and a further object is to so insulate an attachment in the present class as to prevent its enveloping wall from being vibrated by the sounds transmitted through the attachment in speaking, thus to enhance the privacy of telephonic conversation.

In the accompanying drawings, Figure 1 is a view showing my improved attachment in longitudinal sectional elevation and in size considerably enlarged over that in which the device is constructed for use; Fig. 2 is an end view of the same, presenting the end piece; Fig. 3 is a section on line 3, Fig. 1; Fig. 4 is an end view presenting the receiving end of the view in longitudinal sectional elevation of the inner vibratory cylinder and parts contained therein, showing a modification of the diaphragms, and Fig. 6 is a face view of one of the two diaphragms of Fig. 5.

A hollowcylinder 7, of sheet-metal, terminates at one end in an outwardly tapering member-forming section 8, in the form of a cone-frustum. These members are of very thin sheet-metal, preferably steel, to render them highly sensitive to vibration under the influence of sound passing through the device. Concentrically within the section 8, and spaced therefrom, is a.

a citizen of the United States, residing to be attached to a telephone mouthattachment; Fig. 5 is a broken similar tapering member 9, of very thin sheet-metal.

A spiral spring 10, of very fine springwire, and formed preferably of two connected coils, as shown,1s supported centrally 1n the cylinder 7 by an equally fine wire 11, fastened at one end to the inner cylinder-wall andl'at its opposite end to the i by soldering, to cover vtheinner end of the member 9, in spaced relation thereto, a diaphragmforming disk 12 of very thin sheet metal, preferably steel; and a similar diahollow cylinder 14, of relatively thick metal,

preferably aluminum, though it may be a spring 19 between its coils On the outer. v end of one coil is fastened, at its centerpas V phragm 1-3 is fastened in. the same manner. on the outer end of the other coil. A rigid 16 spacing apart the two cylinders and having secured to it the marginal flange 17 of the rounded neck-portion of an outwardly fiarlng tubular extension 17 of the cylinder 7, this extension being preferably corru-' gated circumferentially, as. represented, to

increase its surface and augment its sound- I transmitting actlon. An annular washer 18,

preferably of rubber, is secured in the outer edge of a telephone mouthpiece, indicated at 19, whenthe attachment is used as hereinafter descrlbed. A wire-mesh screen 20 is shown tobe provided at the inner end of the extension 17, to afford a shieldlagainstm s chievous or accldental lnsertions nto the attachment; and a lip 21 extends in semition the tapering members 8 and 9 through the medium of pins 23 and 24k extending at right-angles to each other through the tapering end-portions of these members, and through the adj acent, portion of the neck 22. A cup-like flange 25 surrounds this neck near its outer end and forms with the lat- ,85 face of the flange 1'7 to bear against the spring-coils These Wheel-like ter an annular socket for confining a mouthpiece 26 at its flange 27, this mouthpiece being preferably removable and hollow or pneumatic and formed of soft rubber.

To use my attachment it is applied to a receiver 19 by hooking over the latter the lip 21, which brings the attachment into close contact, at the washer 18, with the edge of the "receiver. This introduces the flaring extension 17 centrally into the tele- PlIQIIQaIBCGlVQI and into desirably close proximity to the diaphragm thereof, w'l'i'ile rigidly supporting the attachment in alinement w-ith the receiver mouthpiece 19.

The user, with lips inserted into the mouthpiece 26, directs speech or other form of sound into the telephone through the attachment. The parts 9, 8 and 7 and the spring-connected and supported diaphragms 12 and 13, are so delicately vibratory and in such relation to each other that the sounds vibrate them and the extensions 17 and becomes progressively augmented to a degree that when even it is merely whispered it so amply vibrates the diaphragm in the telephone-receiver as to be distinctly audible at the receiving end of the telephone.

Without the dead-air space 15 enveloping the vibratory elements of the attachment,

even speech in a. subdued tone or whisper might be auchble to one 111 a position to overhear the telephonecon-versation, when it isdes'ired to keep it secret. The dead-air space, however, prevents transmission of the vibrations to the enveloping cylinder '14, and thus renders the speechinaudible, or at least unintelligibly audible to persons lnthe same roomwith, or in close proximity to the user of the attachment.

The soundaugmenting effect is materially enhanced by providing the diaphragms 12 and 13 in the form, illustrated in Figs. 5 an'd 6, of bladed or vaned Wheels 12 and 13%, like those used in electric fans, and journaling' them on the outer ends of the 10, then forming journals.

diaphragms, which are vibrated, like the corresponding diaphragms 12 and 13, by the sound-waves of speech, are also rotated thereby on the journals; and in revolving they "tend to direct the sound more or less forcibly from the wheel 12 against the cylinder 7, and from the latter through the wheel 13 which directs them in a similar Way through the flaring tubular extension 17 While I have herein mentioned my attacjhment only as applicable to telephone transmitters, it is also intended for use on dictaphones and speaking-tubes.

I realize that considerable variation is possible in the details of construction thus specifically shown and described, and I do notintend by illustrating a single specific or preferred embodiment of my invention to be limited thereto, my intention being in the following claims to claim protection upon all the novelty there may be in my invention as fully as the state of the art will permit.

lVhat I claim as new and desire to secure by Letters Patent is 1. An attachment of the character described, comprising a forwardly flaring member of very thin material open at its ends, and provided at its smaller end with a mouthpiece, a diaphragm of similarly thin material vibratorily supported to extend adjacent to the flaring end of said member, and a sound-insulating chamber enveloping said member and diaphragm.

2. An attachment of the character described, comprising' a forwardly flaring member of very thin material open at its ends and provided at its smaller end with a mouthpiece, a diaphragm and a spring, both of similarly thin material, the spring supporting the diaphragm near its center to extend adjacent to the flaring end of said member and vibrate freely throughout, and a sound-insulating chamber enveloping said member and diaphragm.

3. An attachment of the character described, comprising an inner thin hollow cylinder terminating at its rear end in an outwardly tapering member, soun dqibrated members of thin sheet-metal supported within said cylinder, an outer cylinder of relatively thick material surrounding and forming about the inner cylinder a soundinsul-ating air-space, a mouthpiece on the rear end of said outer cylinder and an outwardly flaring tubular extension on the forward end thereof.

4. In an attachment of the character described, the combination of an inner hollow cylinder, sound-vibrated members of thin sheet-metal within said cylinder, and an outwardly flaring circumferentially corru gated tubular extension at the front end of said cylinder.

5. In an attachment of the character described, the combination of a thin hollow cylinder terminating at its rear end in an outwardly tapering member, a similar member supported within and in spaced relation to said first-named member, a tubularextension at the forward end of said cylinder, and a spring-carried diaphragm interposed in said cylinder between and in alinement with said inner tapering member and flaring extension.

6. In an attachment of the character described, the combination of a'ho'llow cylinder of thin sheet-metal, and a bladed-wheellike diaphragm spring-supported rotatably in said cylinder to be interposed centrally in the passage therethrough.

7. In an attachment ofthe character described, the combination of a hollow cylinder of thin sheet-metal terminating at its rear end in an outwardly tapering member, a similar member supported within and in spaced relation to said first-named member, a spring-carried spring extending lengthwise in said cylinder, a diaphragm on the outer end of the lengthwise-extending spring in alinement with and spaced from the flaring end of saidinner member, and a diaphragm on the opposite end of the lastnamed spring and alining with said firstnamed diaphragm. I

8. In an attachment of the character described, the combination of a hollow cylinder of thin sheet-metal terminating at its rear end in an outwardly tapering member, a similar member supported within and in spaced relation to said first-named member, a spring-carried spring extending lengthwise in said cylinder, a bladed wheel-like diaphragm journaled on one end of the lengthwise-extending spring in alinement with and spaced from the flaring end of said inner member, and a diaphragm on the opposite end of the last-named spring and alining with said first-named diaphragm.

9. In an attachment of the character described, the combination of a hollow cylinder of thin sheet-metal terminating at its rear end in an outwardly tapering member, a similar member supported within and in spaced relation to said first-named member, a spring extending into said cylinder from its wall, a spiral spring formed of end-coils alinedly connected together and connected between the coils with the inner end of said first-named spring to be vibratorily supported thereby and extend lengthwise in said cylinder, a diaphragm on the outer end of one of the rear coils in spaced relation to the flaring end of said inner member, and a diaphragm on the opposite end of the forward coil.

10. An attachment of the character described, comprising an inner hollow cylinder of thin sheet-metal terminating at its rear end in an outwardly tapering member, a similar member supported within and in spaced relation to said first-named member, a spring-carried spring extending lengthwise in said cylinder, a diaphragm on the outer end of the lengthwise-extending spring in alinement with and spaced from the flaring end of said inner member, a diaphragm on the opposite end of the last-named spring and alining with said first-named diaphragm, an outer cylinder enveloping said inner cylinder and forming about the latter a sound-insulating air-space, a mouthpiece on the rear end of the outer cylinder and a tubular extension on the forward end thereof, and means in the outer cylinder for separably connecting it with a telephonetransmitter mouthpiece.

WALTER CLARKE BELLOWS.

In presence of- A. G. FISCHER, C. C. BRENER.

copies 0! this patent may be obtained to: five cents each, by addrelsing the commissioner of Patents, Washington, D. G. 

